Development of a Dry-Type Iron-Core Power Reactor Interturn Insulation Detection Device Based on Frequency Conversion Resonance Technology

Dry-type iron-core power reactors in service often experience coil burnout accidents, leading to serious faults in the power system. The existing insulation detect methods are only applicable to dry-type air-core power reactors, which can cause uneven voltage distribution in iron-core power reactors. Therefore, it is particularly important to develop a lightweight and suitable dry-type iron-core power reactor interturn insulation detection device for on-site detecting. This article first proposes a frequency conversion resonance scheme suitable for the interturn insulation detection of dry-type iron-core power reactors, and based on the new IGBT power module technology, develops a interturn insulation detection device with power electronic transformer technology as the core. The resonant device outputs a maximum voltage of 700 V, a maximum current of 250 A, and a maximum frequency of 5 kHz, with a maximum capacity of 20 kVA, which can meet the interturn insulation detection of dry-type iron-core power reactors with a rated voltage level of 10 kV; Through high-frequency and modular design, the device is miniaturized and suitable for on-site testing. Secondly, to verify the feasibility of the experimental device, a simulation model of interturn insulation detection was constructed. The simulation results showed that the experimental device developed in this paper can be used for interturn insulation detection of dry-type iron-core power reactors. Based on the trend of current changes in series resonant circuits caused by interturn short circuits, a criterion for turn insulation short circuits is proposed, which is to reduce the fault current to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{3 0 \%}$</tex>. Finally, a dry-type iron-core power reactor interturn insulation detection platform was established, with a 10 kV dry-type iron-core series reactor as the test equipment. Through simulation of turn to turn short circuit faults, interturn insulation detections were conducted. The experimental results show that the experimental device developed in this paper can meet the requirements of on-site dry-type iron-core power reactor interturn insulation detecting.